MPEG-4 streaming system with adaptive error concealment

Abstract

An MPEG-4 system with error concealment is provided for video service under the network with packet loss. The MPEG-4 system includes an encoder and a decoder. The encoder uses an intra-refreshment technique is used to make coded bitstream more robust against noise in order to stop error propagation. The rate-distortion optimization criterion is also introduced to adaptively update in synchronization with intra-coded blocks adaptively based on the true network condition with minimal overhead. The Lagrange multiplier is modified to achieve the best rate-distortion balance. In addition, a decoder loop is used in the encoder and is synchronized with the true decoder to achieve the best performance and avoid mismatch with the decoder used in the MPEG-4 system. The decoder is able to achieve resilient decoding from any kind of noise and enhance the reconstructed image quality with spatial and temporal hybrid concealment method. The result shows that a 3.65-9.71 dB further improvement on peak-signal-to-noise-ratio (PSNR) can be achieved in comparison with the existing methods that adopt spatial copy and zero motion concealment in decoding.

1. An error concealment method, combining a hybrid concealment scheme and block-based refinement, comprising the steps of:
 (1) determining if a lost macro block is an intra surrounding macro block; 
 (2) proceeding to step (9) if the lost macro block is an intra surrounding macro block; 
 (3) determining if the lost macro block is a fast motion macro block; 
 (4) proceeding to step (9) if the lost macro block is a fast motion macro block; 
 (5) dividing the lost macro block into 4 sub-blocks and determining a concealment order for the 4 sub-blocks; 
 (6) performing a boundary matching algorithm for the lost macro block to generate a boundary matching result; 
 (7) setting a flag and proceeding to step (9) if the boundary matching result exceeds a boundary matching threshold; 
 (8) performing motion compensation; 
 (9) performing a macro block and block based spatial concealment; and 
 (10) repeating step (1) to step (9) for a next lost macro block; 
 wherein in step (5) the concealment order for the sub-blocks is determined based on validation of four surrounding macro-blocks and locations of the sub-blocks, the four surrounding macro blocks including right, left, top and bottom neighboring macro blocks of the lost macro block.